This invention relates to handling systems for lamellae. While the invention is particularly suitable for use with systems for handling printed circuit board blanks during the production process and before the application of components thereto, the invention may be applied to handling systems for other lamellae in the form of rigid or semi-rigid or flexible sheets, plates, cards or the like; the invention is particularly concerned with systems whereby such lamellae are held at only one edge and on one face to avoid damage to the other broad surfaces of the lamellae or, for example, to fragile or uncured coatings thereon. The invention is particularly applicable to sheets which are fairly limp or flexible but can be applied to rigid lamellae also.
In the production of printed circuit boards, substrates are subjected to various manufacturing processes. In some of these processes the boards themselves have surfaces which can easily be damaged; in other cases, at least one surface of the finished or semi-finished board is provided with a coating; before this coating fully hardens, it can be damaged by contact with another board, with handling means or with anything else. The processes are semi-continuous and the boards may be carried on a conveyor slowly through a processing station. Devices have been produced for accumulating boards from the conveyor and holding them in a compact but non-touching arrangement, for example prior to removal to another operating station or while a coating thereon hardens. In one such accumulator there is a continuous conveyor; the surface of the conveyor is provided by a plurality of parallel slats or profiles which extend across the conveyor and each of which is generally U-shaped in section, the slats being mounted on a pair of chain loops which pass around sprockets at each end of the conveyor. The bottom of each U is attached to the drive chains with the opening of the U extending upwardly when the U is travelling along the upper pass of the conveyor and the U has a flared mouth. At each end of the conveyor, as the drive chains pass around the sprockets, adjacent slats are fanned out and, when halfway round the sprockets, the mouth of the U faces horizontally. As each slat reaches the horizontal position at the receiving end, a printed circuit board has one edge inserted in the slat so that, as the conveyor continues to move, the slat is gradually transferred from a horizontal position to an approximately vertical position and travels in this position along the conveyor towards the opposite end. Printed circuit boards may be fed into the slats by hand or there may be an input conveyor directing boards to the slats. The upper pass of the conveyor may be sufficiently long to enable the machine to accumulate 50 to 100 boards or more. Unless the boards are to be directed to a delivery conveyor (in which case they may be returned to the horizontal at the discharge end of the conveyor), the boards have to be removed one by one by hand and may then be transferred by an operator into storage racks. This handling is time consuming and unless it is done with care damage can be done to the delicate boards. Machines are available having a swinging and translating arm which mechanically removes boards one by one from a conveyor to a stack but this is expensive and does not avoid the problem of damage to the boards by contact with other boards.